Cis, endo-2-azabicyclo-[3.3.0]-octane-5-carboxylic acids

ABSTRACT

Compounds of the formula I ##STR1## in which the carboxyl group on carbon atom 3 is orientated in the endo-position relative to the bicyclic ring system of cis-configuration, and in which R 1  denotes hydrogen, allyl, vinyl or a side-chain of a naturally occurring α-aminoacid, which may be protected, R 2  denotes hydrogen, alkyl, alkenyl or aralkyl, Y denotes hydrogen or hydroxyl and Z denotes hydrogen, or Y and Z together denote oxygen, and X denotes alkyl, alkenyl or cycloalkyl, or aryl which is optionally mono-, di- or tri-substituted by alkyl, alkoxy, hydroxyl, halogen, nitro, amino, alkylamino, dialkylamino or methylenedioxy, or denotes indol-3-yl, a process for their preparation, agents containing these compounds and their use.

This is a continuation of pending application Ser. No. 07/071,147 filedJuly 8, 1987, now abandoned; which in turn is a continuation ofapplication Ser. No. 06/658,902 filed Oct. 9, 1984, now U.S. Pat. No.4,727,160 granted Feb. 23, 1988; which in turn is a divisional ofapplication Ser. No. 06/477,081 filed Mar. 21, 1983 and now abandoned;which in turn is a continuation-in-part of application Ser. No.06/438,757 filed Nov. 3, 1982 and now abandoned.

The invention relates to cis,endoazabicyclo-[3.3.0]-octanecarboxylicacids of the formula I ##STR2## in which the hydrogen atoms on thebridge-head carbon atoms 1 and 5 are in the cis-configuration relativeto one another and the carboxyl group on carbon atom 3 is orientated inthe endo-position relative to the bicyclic ring system, and in which

R¹ denotes hydrogen, allyl, vinyl or a side-chain of a naturallyoccurring α-aminoacid R¹ --CH(NH₂)--COOH, which may be protected,

R² denotes hydrogen, (C₁ -C₆)-alkyl, (C₂ -C₆)-alkenyl or (C₆-C₁₂)-aryl-(C₁ -C₄)-alkyl, which can be mono-substituted by nitro,

Y denotes hydrogen or hydroxyl and

Z denotes hydrogen, or

Y and Z together denote oxygen, and

X denotes (C₁ -C₆)-alkyl, (C₂ -C₆)-alkenyl or (C₅ -C₉)-cycloalkyl, or(C₆ -C₁₂)-aryl, preferably phenyl, which can be mono-, di- ortri-substituted by (C₁ -C₄)-alkyl, (C₁ -C₄)-alkoxy, hydroxyl, halogen,nitro, amino, (C₁ -C₄)-alkylamino, di-(C₁ -C₄)-alkylamino and/ormethylenedioxy, or denotes indol-3-yl,

and physiologically acceptable salts thereof.

Compounds of the formula I in which

R¹ denotes methyl, the side-chain of lysine, which may be acylated, orthe O-(C₁ -C₆)-alkylated side-chain of tyrosine,

R² denotes hydrogen, methyl, ethyl or benzyl,

X denotes phenyl, or phenyl which is mono- or di-substituted by fluorineand/or chlorine,

Y denotes hydrogen or hydroxyl and

Z denotes hydrogen, or

Y and Z together denote oxygen,

are preferred.

Naturally occurring α-aminoacids are, for example, Ala, Val, Len, Ile,Phe, Ser, Thr, Lys, Hyl, Arg, Asp, Asn, Glu, Gen, Cys, Met, Tyr, Pro,Hyp, Trp, His, Orn and Cit.

In this context and in the following text (C₆ -C₁₂)-aryl is to beunderstood as meaning preferably biphenylyl, naphthyl, or especiallyphenyl.

If R¹ represents a side-chain of a protected naturally occurringα-aminoacid, such as, for example, protected Ser, Thr, Asp, Asn, Glu,Gln, Arg, Lys, Hyl, Cys, Orn, Cit, Tyr, Trp, His or Hyp, the groupscustomary in peptide chemistry are preferred as protective groups (cf.Houben-Weyl, Volume XV/1 and XV(2)). In the case where R¹ denotes theprotected lysine side-chain, the known amino-protective groups arepreferred, especially (C₁ -C₆)-alkanoyl. Preferred O-protective groupsfor tyrosine are methyl or ethyl.

The compounds of formula I, having both acidic and basic groups, areamphoteric compounds. Electrically neutral moleculs of I exist in theform of zwitterions.

An acidic group is especially the 3-carboxy group. If R² denoteshydrogen and/or R¹ denotes a side-chain of a acidic aminoacid (e.g. Glu,Asp) two or three additional acidic groups are present in the molecule.Di- and tri-basic acids of formula I can form acidic (hydrogen) salts bypartial neutralisation of the acid. Particularly suitable base additionsalts are alkali metal salts and alkaline earth metal salts (for exampleCa, Mg and Zn salts), and salts with physiologically tolerated amines.

An basic group is especially the --NH--group in the main chain. If Xdenotes (C₆ -C₁₂)-aryl which is substituted by amino, alkylamino ordialkylamino and/or R¹ denotes a side chain of a basic amono acid (e.g.Arg, Lys, Hyl, Orn, Cit, His) two or more basic groups are present inthe molecule. Compounds of formula I having two or more basic groups canform normal salts wherein all the basic groups are neutralised, but alsosalts by partial neutralisation of these groups.

Particularly suitable acid addition salts are salts with physiologicallytolerable inorganic or organic acids, such as, for example HCl, HBr, H₂SO₄, H₃ PO₄, maleic acid, furmaric acid and tartaric acid.

The chirality centers on the carbon atoms labeled with a star (*) in thechain and on carbon atom 3 of the bicyclic ring system can have eitherthe R-configuration or the S-configuration. However, compounds in whichthese centers are in the S-configuration are preferred. If --NH--*CHR¹--CO-- represents Cys, however, the R-configuration of this center ispreferred.

The invention furthermore relates to a process for the preparation ofthe compounds of the formula I, which comprises reacting a compound ofthe formula II in which R² has the abovementioned meanings, with theexception of hydrogen, with a compound of the formula IIIa or IIIb, inwhich W denotes a carboxyl-esterifying group, such as (C₁ -C₆)-alkyl or(C₇ -C₈)-aralkyl (e.g. benzyl, phenethyl or xylyl) preferablytert.-butyl or benzyl, by the known amide formation methods of peptidechemistry, and then liberating the compounds of type I by hydrogenationor treatment with an acid or/and base. ##STR3##

Compounds of the formula II in which X is phenyl, Y is H, Z is H and R²is CH₃ or C₂ H₅ are known (for example from European Patent 0,037,231),and are accessible in various ways. The benzyl ester (R² =benzyl) can beprepared analogously.

It has furthermore been found that the Mannich reaction of acetophenonesof the formula IVa, in which X represents aryl which is optionallysubstituted as described above, with glyoxylic acid esters andα-aminoacid esters leads to compounds of the formula II in which Y and Ztogether denote oxygen (formula IV). In formula IV, W' denotes a radicalwhich can be split off by basic or acidic hydrogenolysis, preferablybenzyl or tert.-butyl, X represents aryl which is optionally substitutedas described above and R¹ and R² have the abovementioned meanings.However, in the case of the benzyl ester (W'=benzyl), R² may not bebenzyl. Hydrogenolysis of these compounds with Pd gives compounds of theformula II in which Y and Z are hydrogen. ##STR4##

Compounds of the formula II in which Y and Z together denote oxygen canalso be obtained in high yields by Michael addition of correspondingketo-acrylic acid esters with α-aminoacid esters. Ester cleavage leadsto the same products as the Mannich reaction. ##STR5##

When L-alanine esters are used, the diastereomers with the preferredS,S-configuration are predominantly formed, and can be isolated bycrystallization or by chromatographic separation of the esters of II onsilica gel.

It has furthermore been found thatcis,endo-2-azabicyclo[3.3.0]octane-3-carboxylic acid esters of theformulae III a and b are accessible from enamines of cyclopentanone ofthe formula VI, in which X¹ represents dialkylamino with 2 to 10 carbonatoms or a radical of the formula VII, in which m and o denote integersfrom 1 to 3, (m+o)≧3 and A denotes CH₂, NH, O or S, ##STR6## andN-acylated β-halogeno-α-amino-carboxylic acid esters of the formulaVIII, in which X² represents a nucleofugic group, preferably chlorine orbromine, Y¹ represents alkanoyl with 1 to 5 carbon atoms, aroyl with 7to 9 carbon atoms or other protective groups which are customary inpeptide chemistry and can be split off under acid conditions, and R²represents alkyl with 1 to 5 carbon atoms or aralkyl with 7 to 9 carbonatoms ##STR7## or with acrylic acid esters of the formula IX, in whichY¹ and R² have the above meanings, ##STR8## by reacting these startingmaterials to give compounds of the formula X, in which R² and Y¹ havethe above meanings, ##STR9## cyclizing these compounds with the aid ofstrong acids, with acylamide and ester cleavage, to give compounds ofthe formula XI a or b ##STR10## converting these into compounds of theformula IIIa or b, in which W represents hydrogen, by catalytichydrogenation in the presence of transition metal catalysts or byreduction with borane-amine complexes or complex borohydrides in loweralcohols, and optionally esterifying the products to give compounds ofthe formula III a or b in which W represents alkyl with 1 to 6 carbonatoms or aralkyl with 7 to 8 carbon atoms.

The bicyclic aminoacids of the formulae IIIa and b have thecis,endo-configuration, i.e. the --CO₂ W group faces the cyclopentanering. All the other 2-azabicyclo[3.3.0]-octane-3-carboxylic acidderivatives mentioned in the present invention are also in thecis,endo-configuration.

Examples of preferred enamines are pyrrolidinocyclopentene andmorpholinocyclopentene. Cyclization of the alkylation products of theformula X is preferably carried out with aqueous hydrochloric acid. Thecompounds of the formula III (in which W is H) can be esterified by themethods customary for aminoacids (cf. for example, Houben-Weyl, Methodender organischen Chemie (Methods of Organic Chemistry), Volume VIII(1952)), for example with thionyl chloride/benzyl alcohol orisobutylene/sulfuric acid. They give, after appropriate working up,compounds of the formula III in the form of the free base or of a salt.

The new compounds of the formula I have a long-lasting, intensehypotensive action. They are powerful inhibitors of theangiotensin-converting enzyme (ACE inhibitors) and can be used forcontrolling high blood pressure of various origins. They can also becombined with other hypotensive, vasodilating or diuretic compounds.Typical representatives of these classes of active compounds aredescribed in, for example, Erhardt-Ruschig, Arzneimittel (Medicaments),2nd edition, Weinheim, 1972. They can be administered intravenously,subcutaneously or perorally. The dosage for oral administration is1-100, preferably 1-50, especially 1-30 mg per individual dose for anadult of normal body weight, i.e. 13-1300 μg/kg/day, preferably 13-650μg/kg/day, especially 13-400 μg/kg/day. In severe cases, it can also beincreased, since no toxic properties have as yet been observed. It isalso possible to reduce the dose, which is appropriate, above all, ifdiuretic agents are administered at the same time.

The compounds according to the invention can be administered orally orparenterally in an appropriate pharmaceutical formulation. For an oraluse form, the active compounds are mixed with the additives customaryfor this form, such as excipients, stabilizers or inert diluents, andthe mixture is converted to suitable administration forms, such astablets, dragees, push-fit capsules, aqueous alcoholic or oilysuspensions or aqueous alcoholic or oily solutions, by customarymethods. Examples of inert carriers which can be used are gum arabic,magnesium stearate, potassium phosphate, lactose, glucose and starch,especially maize starch. The formulation may be prepared in the form ofeither dry or moist granules. Examples of possible oily excipients orsolvents are vegetable and animal oils, such as sunflower oil orcod-liver oil.

For subcutaneous or intravenous administration, the active compounds orphysiologically acceptable salts thereof are dissolved, suspended oremulsified, if desired with the substances customary for this purpose,such as solubilizing agents, emulsifiers or other auxiliaries. Examplesof possible solvents for the new active compounds and the correspondingphysiologically acceptable salts are: water, physiological sodiumchloride solutions or alcohols, for example ethanol, propanediol orglycerol, and in addition also sugar solutions, such as glucose ormannitol solutions, or a mixture of the various solvents mentioned.

The exceptionally powerful activity of the compounds according to theformula I--even when administered orally--is demonstrated by thefollowing pharmacological data.

1. Intravenous administration to anesthetized rats, 50% inhibition ofthe pressor reaction induced by 310 ng of angiotensin I, 30 minutesafter administration of the dose . . . ED₅₀

    ______________________________________                                        X      Y         Z     R.sup.1                                                                              R.sup.2                                                                            ED.sub.50 (μg/kg)                       ______________________________________                                        C.sub.6 H.sub.5                                                                      H         H     CH.sub.3                                                                             C.sub.2 H.sub.5                                                                    8.3                                        C.sub.6 H.sub.5                                                                      H         H     CH.sub.3                                                                             H    2.7                                        ______________________________________                                    

2. Intraduodenal administration to anesthetized rats

    ______________________________________                                        X         Y      Z       R.sup.1                                                                             R.sup.2                                                                             ED.sub.50 (μg/kg)                     ______________________________________                                        C.sub.6 H.sub.5                                                                         H      H       CH.sub.3                                                                            C.sub.2 H.sub.5                                                                      50                                      C.sub.6 H.sub.5                                                                         H      H       CH.sub.3                                                                            H     600                                      C.sub.6 H.sub.5                                                                         --     O       CH.sub.3                                                                            CH.sub.3                                                                            350                                      C.sub.6 H.sub.5                                                                         --     O       CH.sub.3                                                                            C.sub.2 H.sub.5                                                                     280                                      C.sub.6 H.sub.5                                                                         --     O       CH.sub.3                                                                            H     720                                      C.sub.6 H.sub.5                                                                         --     O       CH.sub.3                                                                            C.sub.7 H.sub.7                                                                     250                                      C.sub.6 H.sub.5                                                                         H      OH      CH.sub.3                                                                            C.sub.2 H.sub.5                                                                     380                                      p-Cl--C.sub.6 H.sub.4                                                                   H      H       CH.sub.3                                                                            C.sub.2 H.sub.5                                                                      55                                      p-Cl--C.sub.6 H.sub.4                                                                   --     O       CH.sub.3                                                                            H     780                                      ______________________________________                                    

3. On oral administration to conscious rats, a dosage of 1 mg/kg of, forexample, the compound of the formula I in which X is phenyl, Y and Z areeach H, R¹ is CH₃ and R² is ethyl exhibits 90% inhibition, lasting over6 hours, of the pressor reaction triggered off by intravenousadministration of angiotensin I.

The Examples which follow are intended to illustrate the proceduresaccording to the invention, without restricting the invention to thesubstances mentioned here as representatives.

EXAMPLE IN-(1-S-Carbethoxy-3-phenyl-propyl)-S-alanyl-2-cis,endoazabicyclo-[3.3.0]-octane-3-S-carboxylicacid

(1) Methyl 2-acetylamino-3-(2-oxo-cyclopentyl)-propionate:

269 g of methyl 3-chloro-2-acetylamino-propionate and 257 g ofcyclopentenopyrrolidine in 1.5 liters of dimethylformamide were kept atroom temperature for 24 hours. The mixture was concentrated in vacuo,the residue was taken up in a little water and the aqueous mixture wasadjusted to pH 2 with concentrated hydrochloric acid and extracted twicewith 4 liter portions of ethyl acetate. On concentration of the organicphase, a light yellow oil remained.

Yield: 290 g.

NMR: 2.02 (s,3H); 3.74 (s 3H); 4.4-4.8 (m,1H) (CDCl₃).

    ______________________________________                                        Analysis:                                                                               C          H      N                                                 ______________________________________                                        calculated  58.1         7.54   6.16                                          found       58.5         7.2    6.5                                           ______________________________________                                    

(2) cis,endo-2-Azabicyclo-[3.3.0]-octane-3-carboxylic acid hydrochloride

270 g of the acetylamino derivative prepared under (1) were boiled underreflux in 1.5 liters of 2N hydrochloric acid for 45 minutes. The mixturewas concentrated in vacuo, the residue was taken up in glacial aceticacid, 5 g of Pt/C (10% of Pt) were added and hydrogenation was carriedout under 5 bar. After filtration, the mixture was concentrated and theresidue was crystallized from chloroform/diisopropyl ether.

Melting point: 205°-209° C.,

Yield: 150 g.

(3) Benzyl cis,endo-2-azabicyclo-[3.3.0]-octane-3-carboxylatehydrochloride

40 g of the carboxylic acid prepared under (2) were added to an ice-coldmixture of 390 g of benzyl alcohol and 65 g of thionyl chloride and themixture was left to stand at room temperature for 24 hours. Afterconcentration in vacuo, 47 g of the benzyl ester were crystallized fromchloroform/isopropanol.

Melting point: 175° C. (hydrochloride).

(4) BenzylN-(2-S-carbethoxy-3-phenyl-propyl)-S-alanyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylate

14 g of the benzyl ester prepared according to (3) were reacted with 6.7g of HOBt, 13.8 g of N-(1-S-carbethoxy-3-phenyl-propyl)-S-alanine and10.2 g of dicyclohexylcarbodiimide in 200 ml of dimethylformamide. Afterthe mixture had been stirred for 3 hours at room temperature, thedicyclohexylurea which had precipitated was filtered off with suction,the filtrate was concentrated, the residue was taken up in 1 liter ofethyl acetate and the mixture was extracted by shaking with 3×500 ml of5 percent strength NaHCO₃ solution. The organic phase was concentratedand the residue was chromatographed over a column of 1 kg of silica gelusing ethyl acetate/petroleum ether in the ratio 2:1. The isomer elutedfirst was the S,S,S-compound, and concentration of a later eluate gavethe S,S,R-compound.

In each case 8.0 g of product were obtained as an oil.

NMR: of the S,S,S-compound: characteristic signals: 1.20 (d,3H), 1.27(t,2H), 4.17 (q,3H), 5.13 (s,2H), 7.18 (s,5H) and 7.32 (s,5H) (CDCl₃).

    ______________________________________                                        Analysis C.sub.30 H.sub.38 N.sub.2 O.sub.5                                              C          H      N                                                 ______________________________________                                        calculated  71.1         7.56   5.53                                          found       70.8         7.8    5.7                                           ______________________________________                                    

(5)N-(1-S-Carbethoxy-3-phenyl-propyl)-S-alanyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylicacid

8.0 g of the L,L,L-benzyl ester from (4) were dissolved in 100 ml ofethanol and were debenzylated hydrogenolytically under normal pressure,with addition of 0.5 g of 10% Pd/C. This reaction could also have beencarried out under pressure, together with a shortening of the reactiontime. After the calculated amount of hydrogen had been taken up, thecatalyst was filtered off and the residue was concentrated in vacuo. Thezwitter ion crystallized from ether, in almost quantitative yield.

Melting point: 110°-112° C. (decomposition).

A hydrochloride (decomposition from 120° C.) can be obtained by additionof an equivalent amount of hydrochloric acid, or a zinc complex saltswhich is particularly stable to heat (decomposition above 160° C.) canbe obtained by addition of aqueous zinc salts to a concentratedmethanolic solution of the title compound.

    ______________________________________                                        Analysis C.sub.23 H.sub.32 N.sub.2 O.sub.5                                              C          H      N                                                 ______________________________________                                        calculated  66.3         7.7    6.73                                          found       66.1         7.8    6.6                                           ______________________________________                                    

The NMR and mass spectra obtained are in agreement with the givenstructure.

[α]_(D) =+15.6° (c=1, methanol).

EXAMPLE II

(1) tert.-Butyl cis,endo-2-azabicyclo-[3.3.0]-octane-3-carboxylate

25 g of azabicyclo-[3.3.0]-octane-carboxylic acid hydrochloride fromExample I (2) were reacted with 250 ml of isobutylene and 25 ml ofconcentrated sulfuric acid in 250 ml of dioxane. After 14 hours at roomtemperature, the mixture was rendered alkaline with sodium hydroxidesolution and concentrated in vacuo, 100 ml of water were added and theester was extracted with ether. Evaporation of the ether gave 15 g of acolorless oil.

    ______________________________________                                        Analysis C.sub.12 H.sub.21 NO.sub.2                                                     C          H      N                                                 ______________________________________                                        calculated  68.2         10.2   6.63                                          found       67.9         10.1   6.3                                           ______________________________________                                    

(2) N-(1-S-Carbobenzyloxy-3-oxo-3-phenyl-propyl)-S-alanine tert.-butylester

12.0 g of acetophenone, 17 g of benzyl glyoxylate and 31.7 g of alaninetert.-butyl ester toluenesulfonate were heated to 45°-50° C. in 200 mlof glacial acetic acid for 24 to 48 hours. The reaction was monitored bythin layer chromatography and was interrupted at the optimum reactionpoint. The mixture was concentrated thoroughly in vacuo, the residue wasrendered basic with aqueous bicarbonate solution and the mixture wasextracted with ethyl acetate. The organic phase was concentrated assubstantially as possible and the S,S-isomer was crystallized fromcyclohexane/petroleum ether. The R,S-compound remained substantially insolution. To obtain seed crystals, chromatography of the crude mixtureon silica gel in a 2:1 cyclohexane:ethyl acetate system to which 0.1% oftriethylamine had been added was advisable. The S,S-compound was elutedas the second of the two diastereomers and was obtained in the largeramount. 9 g were obtained.

    ______________________________________                                        Analysis C.sub.24 H.sub.29 NO.sub.5                                                     C          H      N                                                 ______________________________________                                        calculated  70.1         7.1    3.4                                           found       70.0         6.9    3.5                                           ______________________________________                                    

(3) N-(1-S-Carbobenzyloxy-3-oxo-3-phenyl-propyl)-S-alaninetrifluoroacetate

8 g of the Mannich condensation product from (2) were dissolved in 25 mlof anhydrous trifluoroacetic acid and the solution was left at roomtemperature for one hour. The solution was concentrated in vacuo,diisopropyl ether was added and the product was precipitated withpetroleum ether. 7.2 g of an amorphous substance were obtained.

    ______________________________________                                        Analysis C.sub.22 H.sub.22 NO.sub.7 F.sub.3                                             C          H      N                                                 ______________________________________                                        calculated  56.3         4.7    3.0                                           found       56.0         4.8    3.1                                           ______________________________________                                    

Molecular weight: 469.

(4) tert.-ButylN-(1-S-carbobenzyloxy-3-oxo-3-phenyl-propyl)-S-alanyl-2-cis,endo-azabicyclo-[3.3.0]-octane-3-carboxylate

35.5 g of the N-substituted alanine from (3) were reacted with 21.1 g ofthe tert.-butyl azabicyclooctanecarboxylate from Example II (1)analogously to Example I (4). Chromatography over silica gel gave 20.3 gof the title compound.

    ______________________________________                                        Analysis C.sub.32 H.sub.40 N.sub.2 O.sub.6                                              C          H      N                                                 ______________________________________                                        calculated  70.04        7.35   5.10                                          found       69.6         7.4    5.3                                           ______________________________________                                    

(5)N-(1-S-Carbobenzyloxy-3-oxo-3-phenyl-propyl)-S-alanyl-2-cis,endo-azabicyclo-[3.3.0]-octane-3-carboxylicacid

20 g of the tert.-butyl ester from (4) were dissolved in 100 ml oftrifluoroacetic acid and the solution was left to stand at roomtemperature for one hour. The solution was concentrated in vacuo, theresin which remained was taken up in ethyl acetate and the mixture wasneutralized with aqueous bicarbonate. 14 g of the title compound wereobtained from the ethyl acetate phase.

    ______________________________________                                        Analysis C.sub.28 H.sub.32 N.sub.2 O.sub.6                                              C          H      N                                                 ______________________________________                                        calculated  68.27        6.55   5.69                                          found       68.1         6.4    5.7                                           ______________________________________                                    

(6)N-(1-S-Carboxy-3-R,S-hydroxy-3-phenyl-propyl)-S-alanyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-carboxylicacid

1 g ofN-(1-S-carbobenzyloxy-3-oxo-3-phenyl-propyl)-S-alanyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-carboxylicacid were dissolved in 50 ml of ethanol, 150 mg of Pd/BaSO₄ were addedand hydrogenation was carried out under normal pressure. After thecalculated amount of hydrogen had been taken up, the mixture wasfiltered, the filtrate was concentrated and the residue waschromatographed over silica gel in the solvent CHCl₃ /CH₃ OH/CH₃ COOH50:20:5.

Yield: 0.6 g.

(7)N-(1-S-Carbobenzyloxy-3-R,S-hydroxy-3-phenyl-propyl)-S-alanyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-carboxylicacid

1 g ofN-(1-S-carbobenzyloxy-3-oxo-3-phenyl-propyl)-S-alanyl-2-cis,endo-azabicyclo-[3.3.0]-octane-3-carboxylicacid were dissolved in 50 ml of a mixture of acetonitrile and water andwere reduced with 150 mg of NaBH₄. After 12 hours, the mixture wasconcentrated to dryness, the residue was rendered neutral with dilutehydrochloric acid and the title compound was extracted with ethylacetate. To remove boric acid and other impurities, the product waschromatographed over silica gel in the solvent CHCl₃ /CH₃ OH/CH₃ COOH50:10:5.

    ______________________________________                                        Analysis C.sub.28 H.sub.34 N.sub.2 O.sub.6                                              C          H      N                                                 ______________________________________                                        calculated  67.99        6.93   5.66                                          found       67.7         6.6    5.3                                           ______________________________________                                    

EXAMPLE III General method: Hydrolysis of esters to prepare compounds ofthe formula I in which R² is H

10 g of the corresponding ethyl or benzyl ester of the formula I weredissolved in 200 ml of dimethoxyethane. One drop of a dilute indicatorsolution, for example bromothymol blue, was added, and an equivalentamount of 4N KOH (aqueous) was added in the course of 5 minutes, whilestirring vigorously, so that at the end of the reaction the indicatorindicated a pH value of 9-10. The mixture was then adjusted to pH 4 withhydrochloric acid and concentrated to dryness in vacuo, the residue wastaken up in 250 ml of ethyl acetate and the mixture was filtered. Onconcentration of the ethyl acetate, the dicarboxylic acids precipitatedas solid, crystalline or amorphous compounds.

The yields were between 80 and 95%.

EXAMPLE III AN-(1-S-Carboxy-3-phenyl-propyl)-S-alanyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylicacid

1 g ofN-(1-S-carbethoxy-3-phenyl-propyl)-S-alanyl-2-azabicyclo-[3.3.0]-octane-3-S-carboxylicacid from Example I (5) was hydrolyzed (1 hour) and the mixture wasworked up, as described under Example III.

Yield: 0.85 g.

m/e: 388.

EXAMPLE IV N-(1-S-Carbethoxy-3-oxo-3-phenyl-propyl)-S-alanine benzylester

65.7 g of ethyl 4-phenyl-4-oxo-butene-2-carboxylate (ethylbenzoylacrylate) were dissolved in 225 ml of ethanol, and 1 ml oftriethylamine was added. A solution of 70 g of S-alanine benzyl ester in90 ml of ethanol was rapidly added dropwise at room temperature. Themixture was stirred at room temperature for 2 hours and the solution wasthen cooled. The S,S-isomer crystallized out.

Yield: 94.3 g Melting point: 83°-74° C.

[α]_(D) ²⁰ =+17.8° (c=1, CH₃ OH).

EXAMPLE V N-(1-S-Carbethoxy-3-oxo-3-phenyl-propyl)-S-alanine

0.5 g of the compound from Example IV was dissolved in 40 ml of ethanol,0.1 g of 10% Pd/C was added and hydrogenation was carried out at roomtemperature and under normal pressure.

Yield: 300 mg melting point: 210°-220° C.

¹ H-NMR (DMSO-d₆): 1.0-1.4 (t,6H); 3.2-5.0 (m,8H); 7.2-8.2 (m,5H).

EXAMPLE VI BenzylN-(1-S-carbethoxy-3-oxo-3-phenyl-propyl)-S-alanyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylate

The compound was prepared from benzylcis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylate hydrochloride andN-(1-S-carbethoxy-3-oxo-3-phenyl-propyl)-S-alanine from Example V,analogously to the process described in Example I (4).

EXAMPLE VIIN-(1-S-carbethoxy-3-oxo-3-phenyl-propyl)-S-alanyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylicacid

1 g of the benzyl ester from Example VI was dissolved in 30 ml ofethanol and hydrogenated with 100 mg of Pd/C (10%) at room temperatureand under normal pressure. After one mole equivalent of hydrogen hadbeen taken up, the hydrogenation was interrupted. The catalyst wasfiltered off with suction and the solution was concentrated.

Yield: 600 mg of an oil.

¹ H-NMR (DMSO-D₆): 1.0-3.0 (m,15H); 3.3-5.0 (m,10H); 7.2-8.1 (m,5H).

EXAMPLE VIII N.sub.α-(1-S-Carbethoxy-3-phenyl-propyl)-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylicacid dihydrochloride

(1) N.sub.α-(1-S-Carbethoxy-3-oxo-3-phenyl-propyl)-N-benzyloxycarbonyl-S-lysinebenzyl ester

10 g of ethyl 4-phenyl-4-oxo-butene-2-carboxylate were dissolved in 100ml of ethanol. 19.1 g of N.sub.ε -benzyloxycarbonyl-S-lysine benzylester and 0.2 g of triethylamine were added. The solution was stirred atroom temperature for 3 hours and was then concentrated in vacuo. Theoily residue (31 g) was dissolved in isopropanol/diisopropyl ether andthe solution was cooled. 13 g of N.sub.α-(1-S-carbethoxy-3-oxo-3-phenyl-propyl)-N.sub.ε-benzyloxycarbonyl-S-lysine benzyl ester crystallized.

α_(D) ²⁰ =3.5° (c=1, CH₃ OH).

¹ H-NMR (CDCl₃): 1.0-1.4 (tr,3H); 1.0-2.0 (m,9H); 2.0-2.6 (broad s.,1H); 2.9-3.9 (m, 6H); 3.9-4.4 (quadr. 2H); 4.6-4.9 (broad s., 1H);5.0-5.2 (double s., 4H) 7.1-8.1 (m,15H).

(2) N.sub.α -(1-S-Carbethoxy-3-phenyl-propyl)-N.sub.ε-benzyloxycarbonyl-S-lysine

4.0 g of the lysine benzyl ester derivative prepared in Example VIII (1)were dissolved in 50 ml of glacial acetic acid, and 0.6 g of Pd/C (10%)and 0.6 g of concentrated sulfuric acid were added. Hydrogenation wascarried out at room temperature and under normal pressure for 6 hours.The catalyst was then filtered off with suction and the ethanolicsolution was stirred with 1.4 g of solid sodium bicarbonate. Thesolution was concentrated on a rotary evaporator and the residue wasdissolved in water. The aqueous phase was extracted with ethyl acetateand methylene chloride. The organic phases were discarded and theaqueous phase was evaporated to dryness in vacuo. The residue wasextracted by stirring with methanol. After the methanol had beenevaporated off, an oily residue remained, which solidified when treatedwith diisopropyl ether. Yield of N.sub.α-(1-S-carbethoxy-3-phenyl-propyl)-S-lysine: 2.0 g

¹ H-NMR (D₂ O): 1.0-1.4 (tr, 3H); 1.0-2.5 (m, 9H), 2.5-4.4 (m, 9H);3.9-4.4 (q, 2H); 4.5-5.0 (m, 1H); 7.1-7.6 (m, 5H).

m/e: 336

3.4 g of N.sub.α -(1-S-carbethoxy-3-phenyl-propyl)-S-lysine weredissolved in 30 ml of methylene chloride and the solution was cooled to0° C. While cooling with ice, 2.1 g of triethylamine were added, and 1.9g of benzyl chloroformate were then added dropwise. The mixture wasstirred at 0° C. for 1 hour and was then brought to room temperature.The methylene chloride solution was extracted by shaking successivelywith water, sodium carbonate solution and water. After the product phasehad been dried, it was concentrated and the oily residue waschromatographed over silica gel using methylene chloride/methanol. 2.0 gof N.sub.α -(1-S-carbethoxy-3-phenyl-propyl)-N.sub.ε-benzyloxycarbonyl-S-lysine were obtained.

¹ H-NMR (D₂ O): 1.0-1.4 (tr, 3H); 1.0-2.5 (m, 9H); 2.5-4.4 (m, 9H);3.9-4.4 (q, 2H); 4.5-5.0 (m, 1H); 5.1 (s, 2H); 7.1-7.5 (m, 10H).

(3) Benzyl N.sub.α -(1-S-carbethoxy-3-phenyl-propyl)-N.sub.ε-benzyloxycarbonyl-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylate

a) 560 mg of benzyl 2-azabicyclo-[3.3.0]-octane-3-carboxylatehydrochloride prepared according to Example I (3) were reacted with 940mg of N.sub.α -(1-S-carbethoxy-3-phenyl-propyl)-N.sub.ε-benzyloxycarbonyl-S-lysine prepared according to Example VIII (2),analogously to Example I (4). After the mixture had been worked up, 1.5g of an oil, which was a mixture of two diastereomeric compounds, wereobtained.

The diastereomer mixture was separated into the individual components bycolumn chromatography with silica gel and cyclohexane/ethyl acetate 2:1as the eluting agent. The isomer eluted first was the above compound.0.6 g of an oil was obtained.

¹ H-NMR (CDCl₃) (after replacement of H by D with D₂ O): 1.0-2.6 (m,20H); 2.6-4.5 (m, 8H); 4.6-5.0 (m, 2H); 5.1-5.3 (double s., 4H); 7.1-7.6(m, 15H).

b) The later eluate gave 0.4 g of benzyl N.sub.α-(1-S-carbethoxy-3-phenyl-propyl)-N.sub.ε-benzyloxycarbonyl-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-R-carboxylate.

¹ H-NMR (CDCl₃) (after replacement of H by D with D₂ O): 1.0-2.6 (m,20H); 2.6-4.4 (m, 8H); 4.5-5.0 (m, 2H); 5.1-5.3 (double s., 4H); 7.1-7.5(m, 15H).

(4) N.sub.α-(1-S-Carbethoxy-3-phenyl-propyl)-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylicacid dihydrochloride

500 mg of benzyl N.sub.α -(1-S-carbethoxy-3-phenyl-propyl)-N.sub.ε-benzyloxycarbonyl-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylatefrom Example VIII (3a) were dissolved in 20 ml of ethanol and weredebenzylated hydrogenolytically under normal pressure, with addition of0.1 g of 10% Pd/C. When the uptake of hydrogen had ended, the catalystwas filtered off, ethanolic hydrogen chloride solution was added to theethanolic solution until a pH of 1 was reached, and the ethanol wasevaporated off in vacuo. Diisopropyl ether was added to the residue,whereupon the product solidified. 200 mg were obtained.

¹ H-NMR of the betaine (CDCl₃, after replacement of H by D with D₂ O):1.0-2.5 (m, 20H); 2.6-4.4 (m, 8H); 4.4-5.1 (m, 2H); 7.2 (s, 5H)

EXAMPLE IXN-(1-S-Carbethoxy-3-phenyl-propyl)-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-R-carboxylicacid dihydrochloride

0.3 mg of the corresponding benzyl ester from Example VIII (3 b) werereacted, and the mixture worked up, analogously to Example VIII (4). 110mg of the carboxylic acid were obtained in the form of thedihydrochloride.

¹ H-NMR of the betaine (CDCl₃, after replacement of H by D with D₂ O):1.0-2.6 (m, 20H); 2.6-4.4 (m, 8H); 4.1-5.1 (m, 2H); 7.2 (s, 5H).

EXAMPLE XN-(1-S-Carboxy-3-phenyl-propyl)-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylicacid hydrochloride

0.5 g ofN-(1-S-carbethoxy-3-phenyl-propyl)-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-S-carboxylicacid dihydrochloride from Example VIII (4) was suspended in 20 ml ofdimethoxyethane. Aqueous 4N KOH was added until a pH of 9-10 wasreached. The mixture was stirred for half an hour. It was then adjustedto pH 4 with hydrochloric acid and concentrated to dryness in vacuo, theresidue was taken up in ethyl acetate and the mixture was filtered. Theethyl acetate solution was concentrated and the residue was trituratedwith diisopropyl ether, whereupon it solidified.

Yield: 0.35 g.

¹ H-NMR (D₂ O): 1.2-2.5 (m, 17H); 2.5-4.5 (m, 6H); 4.5-5.0 (m, 2H); 7.2(s, 5H).

EXAMPLE XI N.sub.α-(1-S-Carboxy-3-phenyl-propyl)-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-R-carboxylicacid hydrochloride

500 mg of N.sub.α-(1-S-carbethoxy-3-phenyl-propyl)-S-lysyl-cis,endo-2-azabicyclo-[3.3.0]-octane-3-R-carboxylicacid dihydrochloride from Example IX were hydrolyzed, and the mixturewas worked up, analogously to Example X.

Yield: 0.32 g.

¹ H-NMR (D₂ O): 1.2-2.5 (m, 17H); 2.5-4.5 (m, 6H); 4.5-5.0 (m, 2H); 7.2(s, 5H).

EXAMPLE XIIN-(1-S-Carbethoxy-3-phenyl-propyl)-O-ethyl-S-tyrosyl-cis,endo-2-azabicyclo[3.3.0]octan-3-S-carboxylicacid

(1) N-(1-R,S-carbethoxy-3-phenyl-propyl)-O-ethyl-S-tyrosine benzyl ester

Analogously to example IV, 24 g ethyl benzoylacrylate dissolved in 100ml ethanol were reacted with 30 g O-ethyl-S-tyrosine benzyl ester in thepresence of 0.5 ml triethylamine. The solution was concentrated, theresidue was digested with diethylether petroleum ether (1:1) and driedin vacuo. 42 g of the RS, S-compound were obtained.

(2) N-(1-R,S-carbethoxy-3-phenyl-propyl)-O-ethyl-S-tyrosine

40 g of the product from (1) were dissolved in 800 ml glacial aceticacid and the solution was hydrogenated under 100 bar and roomtemperature in the presence of 4 g Pd/C (10 percent). After the crudeproduct had been chromatographed over silica gel in the solvent ethylacetate/cyclohexane 1:3 and the solution had been concentrated todryness, 25 g of the title compound were obtained, which proved to bealmost homogen by thin layer chromatography. Melting point: 205°-213° C.

    ______________________________________                                        Analysis: C.sub.23 H.sub.39 NO.sub.5 (399.5)                                            C          H      N                                                 ______________________________________                                        Calculated  69.15        7.31   5.30                                          Found       69.5         7.4    3.3                                           ______________________________________                                    

(3)N-(1-S-carbethoxy-3-phenyl-propyl)-O-ethyl-S-tyrosyl-cis,endo-2-azabicyclo[3.3.0]octan-3-S-carboxylicacid

Analogously to example I (4), 5 g of the free benzyl ester, obtainedfrom example I (3) by treating with alkali and extracting withdiethylether, were reacted with 8 g of the compound from example XII (2)and 4.4 g dicyclohexyl-carbodiimide in the presence of 2.7 g1-hydroxybenzotriazole. After subsequent chromatography as described inexample I (4) 2.9 g of an oil, which is the intermediate benzyl ester,were obtained.

¹ H-HMR- and mass spectra were in accordance with the given structure.

The benzyl ester was dissolved in 50 ml ethanol, Pd (C) was added andhydrogenation was carried out under normal pressure. The mixture wasfiltered, the filtrate was concentrated, the residue was digested anddried in vacuo. Yield: 2.2 g.

¹ H-NMR (CDCl₃): 1.2-3.0 (m, 15H), 1.27 (t, 3H), 1.4 (t, 3H), 3.0-4.3(m, 4H), 3.8-4.2 (m, 4H), 6.5-7.1 (2d, 4H), 7.3 (s, 5H).

EXAMPLE XIIIN-(1-S-Carbethoxy-3-phenyl-propyl)-O-methyl-S-tyrosyl-cis,endo-2-azabicyclo[3.3.0]octan-3-S-carboxylicacid

The compound was prepared from O-methyl-S-tyrosine benzyl esteranalogously to the process described in example XII. The ¹ H-NMRspectrum is in accordance with the given structure.

We claim:
 1. A mixture consisting essentially of enantiomers of theformulas ##STR11## or a salt of such enantiomers with an acid or a base,wherein the hydrogen atoms on the bridge-head carbon atoms in the 1- and5-positions are in the cis configuration relative to one another and the--CO₂ W group on the carbon atom in the 3-position is oriented in theendo position relative to the bicyclic ring system, and wherein W ishydrogen, alkyl having 1-6 carbon atoms, or aralkyl having 7 or 8 carbonatoms.
 2. An enantiomer as in claim 1 wherein the carbon atom in the3-position of the bicyclic ring system is in the R-configuration.
 3. Anenantiomer as in claim 1 wherein the carbon atom in the 3-position ofthe bicyclic ring system is in the S-configuration.
 4. A mixtureconsisting essentially of compounds of the formula ##STR12## or a saltof such compounds, wherein the hydrogen atoms on the bridge-head carbonatoms in the 1- and 5-positions are in the cis configuration relative toone another and the --CO₂ W group on the carbon atom in the 3-positionis oriented in the endo position relative to the bicyclic ring system,and wherein W is hydrogen, tert.-butyl, or benzyl.
 5. A mixture ofcompounds as in claim 4 wherein W is hydrogen.
 6. A mixture of compoundsas in claim 4 wherein W is benzyl.
 7. A mixture of compounds as in claim4 wherein W is tert.-butyl.